Lack of Seasonal Differences in Basal Metabolic Rate in Humans: A Cross-Sectional Study

Abstract

Some studies indicate that basal metabolic rate is greater winter than the summer, suggesting a role for brown fat in human thermogenesis. We examined whether there are clinically meaningful differences in basal metabolic rate under thermoneutral conditions between winter and summer months in inhabitants of Rochester, Minnesota. We collated data from 220 research volunteers studied in the winter (December 1 – February 28) and 214 volunteers studied in the summer (June 1 – August 31), 1995–2012. Basal metabolic rate was measured by indirect calorimetry and body composition by dual-energy X-ray absorptiometry. The effect of season on basal metabolic rate was tested using multivariate regression analysis with basal metabolic rate as the dependent variable and fat free mass, fat mass, age, sex, and season as the independent variables. The groups were comparable with respect to age, body mass index, fat mass and fat free mass. There was no significant difference in basal metabolic rate between winter and summer groups (1667±322 vs 1669±330 kcal/day). Both winter and summer basal metabolic rates were strongly predicted by fat free mass (Pearson’s r=0.75 and r=0.77, respectively, p<0.0001). Using multiple linear regression analysis, basal metabolic rate was significantly, independently predicted by fat free mass, fat mass, age and sex, but not season. We conclude that the lack of seasonal variation of thermoneutral basal metabolic rate between winter and summer suggests that modern, Western populations do not engage thermogenically detectable brown fat activity during periods of living in a cold climate.

Estimating the agreement between the metabolic rate calculated from prediction equations and from a portable indirect calorimetry device: an effort to develop a new equation for predicting resting metabolic rate

“…Furthermore, the RMR measurement period (time of year) was not recorded since variations in metabolic rate due to seasonal variations have not been reported in many studies, regarding people who live in a modern western environment and are not exposed to a cold climate. Finally, the absence of the thermogenic effect of brown adipose tissue during seasonal variations has yet not been reported and needs further investigation [ 51 ].…”

Seasonal Body Weight Dynamics in Healthy People: A Meta-Analysis

“…The food was maximally saturated with vitamin A in spring, vitamin C in summer and autumn, and vitamin E in summer [64]. Several studies included in our meta-analysis reported no difference in caloric intake between winter and summer [42,43,53,54]. There were also no differences between men and women in the seasonal dynamics of the amount of calories consumed [43,53].…”

“…Kanikowska et al [38] observed a slight increase in leptin in winter in healthy young men. There are reports of an increase in cholesterol levels in winter without a significant change in triglyceride levels [38][39][40][41][42]. According to the results of some studies, the glucose level did not change during the year [41], according to the results of others, it was higher in winter than in summer [40].…”

Predictive equations for evaluation for resting energy expenditure in Brazilian patients with type 2 diabetes: what can we use?

“…This may have influenced the REE, as the climate is one of the factors that influences its variability. In fact, some studies have already shown a higher REE in winter than in summer [50,51]. However, to minimize these effects we standardized the temperature and humidity of the environment where IC was performed so as to mitigate any seasonal influence on REE.…”